This dissertation examines the logic of immanence and the method of fundamental science ("Wissenschaftslehre") in the philosophy of Nishida Kitarô (1870-1945). Logic (or science) for Nishida concerns the self-determining (self-affective) act, and, for him, this self-affective act is deeply embedded in what I call "openness" of historical reality. According to Nishida, since history is never third-personal, it must be considered from the first-person perspective of a practical agent in that historical reality. This emphasis on immanent (historical) reality separates Nishida's logic from Fichte's doctrines of science. Nishida proposes and examines a few notions to investigate this immanent historical reality, two of which are of particular significance: self-awareness and action-intuition. Throughout the dissertation, I shall examine these two concepts found in Nishida's thought, each of which entails different conceptions of reason, self-knowledge, and action.

A basic principle running throughout Nishida's philosophy is the idea that the unity of apperception is none other than difference as such. There is, however, a gradual shift in emphasis in Nishida's thought around the 1930s from a focus on the former (on self-awareness and its quasi-Dedekind infinity) to the latter (on action-intuition). A key aspect of this shift is Nishida's concept of a noumenal (historical) world and the problem of contingency.

In order to examine the nature of this shift, this dissertation proposes three theses concerning Nishida's thought: theses of rationality, contingency, and exteriority. The three body chapters of this dissertation examine each of the three theses contextualized within the following issues found in Nishida's work: 1) First-person perspective/authority 2) Practical philosophy 3) Historical world (the world of action-intuition) The three theses and their relationship to each other constitute the principle object of investigation of this dissertation. The thesis on contingency mediates Nishida's transition from the early thesis of rationality to the late thesis of exteriority.

To put it differently, I will elucidate Nishida's methods towards a rigorous "science" of history. It is important to keep in mind that Nishida's fundamental "science" (of history) is not simply what Fichte calls "Wissenschaftslehre," but in fact "Wissenschaftslehre" considered vis-à-vis the historical world. Contingency of historical reality is a central issue for Nishida in investigating the nature of rationality.

In general, historical reality is "open" at least in two senses: In the sense that it is dialectical, and that our knowledge of it is fallible. Both issues of "openness" present serious challenges in Nishida's philosophy. That is to say, indeterminacy is an essential condition of such immanently dialectical historical reality. This, I argue, is the basic framework of Nishida's fundamental science.

Although the thesis on self-awareness (jikaku) in Nishida's early work is partially analogous to Fichte's first principle (or Tathandlung), the Fichtean-Kantian system is no longer relevant to Nishida's later thesis on exteriority of action-intuition. Nishida's analysis of self-awareness, a self-representative system, is his initial attempt to establish a rigorous science of history as well as an agent within historical reality. Since an act in the historical world affects both the subject and the object, a historical agent is structured self-reflexively. The historical world, unlike the physical or the biological world, is a world in which such self-affection is inevitable. Given this self-affective structure of historical reality, the concepts of reason and first-person-hood are deeply implicated in one another. This is what I call Nishida's "rationality thesis," the first thesis examined in this dissertation. However, the notion of self-awareness thus conceived does not represent the contingent nature of a conflicted historical agent. The infinity of the historical world is more diverse than a self-representative system of self-awareness. I argue that this is the reason Nishida attempts to reconsider his rationality thesis. In other words, although the quasi-Dedekind-infinity of self-awareness is a model for self-knowledge, it does not account for the fallible, or contingent, nature of an acting person (and self- knowledge) in the historical world. I examine Nishida's action-intuition within a few contexts, including that of late-Wittgenstein's rule-following skepticism, Kuki Shûzô's thoughts on contingency, and Imanishi Kinji's bio-sociology (biosemiotics).

The transition from the logic of self-awareness to that of action-intuition entails a series of conceptual alterations: most importantly, a greater emphasis on the I-thou relation, and the fallibility of act. I conclude that Nishida's second thesis (on openness) on the contingent relationship between the past and the future, or the exteriority of futurity necessitates his gradual shift from the rationality thesis on self-awareness to the thesis on exteriority of action-intuition.